This invention relates to the catalytic enhancement of solid fuel combustion and more particularly to the deposition of the catalyst on a substrate which remains in the furnace.
The catalytic oxidation effect of metals impregnated on solid carbonaceous fuels such as coal and coke has long been known. Such catalysts have been used in coal gasification as reported, for example, in "Application of Catalysts To Coal Gasification Processes, Incentives and Perspectives," Harald Juntgen, Fuel, February 1983, Vol. 62, p. 234.
While catalysts have been used in oxidation/gasification processes, they have not been widely used in combustion operations for the direct extraction of heat, such as in power plants and the like. One reason is that the catalyst is directly impregnated on the solid fuel, is quickly expended and is lost with ash removal. Catalysts have not been extensively used in industrial combustion operations due to concerns over the cost of catalyst loss and possible environmental effects of emitted metal particles.
It is an object of the present invention to deposit a combustion enhancing catalyst on a substrate which remains in a fluidized bed combustor thereby alleviating problems associated with catalyst loss.
It is another object of the present invention to burn solid fuel in a fluidized bed at a temperature which is low enough to allow catalytic influence, i.e., the higher activation energy thermal reactions will not completely overwhelm catalysis.
It is another object of the present invention to use catalysis to increase the throughput for a given unit size or permit the use of a smaller unit for a given duty.
It is another object of the present invention to obviate problems associated with direct impregnation of the catalysts on solid fuel.